1. Field of the Invention
The field of the invention is devices utilized in toilet water reservoir tanks which allow for a partial or full flush of the toilet, the partial flush achieved by limiting the water draining from the reservoir tank into the toilet bowl.
2. Description of the Related Art
Inasmuch as many parts of the United States, and especially the West and the Southwest regions, experience water supply shortages, it has now become very popular to conserve water by reducing water usage. To this end, the toilets found in residences and businesses are being modified to provide for a smaller flush, i.e., the water reservoir tank is being reduced from a five gallon capacity to a two to three gallon capacity. In addition, many devices and inventions are coming forth which permit the user to effect a partial or "mini" flush wherein only a portion of the water held in the reservoir tank is utilized. Experience tends to indicate that a partial flush operates satisfactory for liquid wastes, however, in most cases, a partial or "mini" flush is not satisfactory to remove solid wastes. Accordingly, many of the devices which provide for a partial or "mini" flush also provide for a full flush, the choice being made at the time of use.
One such device is shown in the U.S. Pat. No. 4,149,283 to Knudtson. Here a rather complicated mechanism allows selective manipulation of the toilet tank handle to vary the time that a buoyant drain valve takes to re-seat after the flush is first begun, thus allowing only a part of the contained water to exit the tank.
Another device is shown in the U.S. Pat. No. 3,955,218 to Ramsey, wherein a partial or mini flush is provided for utilizing an air venting hole in the upper region of a bell shaped flapper valve but below its annularly shaped sealing flange. As the outside handle is pushed down, the flapper valve is pulled upward, the flapper valve is pulled upward and pivoted off the valve seat, entrapped air within an inverted bell shaped cavity of the flapper valve is allowed to escape through the air venting hole. It is this entrapped air within the bell shaped cavity that renders the flapper valve buoyant and keeps it from re-seating immediately upon the valve seat. The bell shaped cavity has an opening at its lower end. As air escapes from the cavity, a point is reached where the flapper valve is no longer buoyant in the water, and it returns to the valve seat. The size of the hole is adjusted to regulate the rate of release of air from the contained cavity or plenum over time so that not all the water exits the reservoir tank. A full flush may be accomplished by continuing to hold the outside handle down so that the lever arm attached to the handle continually holds up the flapper valve by a connecting chain.
It is noted that the air vent hole in the flapper valve is placed below the annular flange of the flapper valve which actually seals to the valve seat, otherwise, the vent hole would allow continual escape of water from the reservoir tank.
Lastly, Sullivan, in U.S. Pat. No. 4,145,774 provides for a limited or mini flush by providing the handle of the flush mechanism so constructed that if a limited or mini flush is desired, the handle, after being pushed down, must be manually returned to its pre-flush position by the operator. By such action, the interior flapper valve is freed from action upon it by the lever arm in order that it may return to its seated position after a specified time. Return of the flapper valve to its seated position is accomplished by substantially utilizing the invention of Ramsey wherein air entrapped in the interior plenum or cavity of the bell shaped flapper valve may progressively escape. To effect a normal full flush in Sullivan's device, the operator pushes the handle down at the beginning of the operation. The handle returns to its normal pre-flush position after all the water in the tank has drained.
The above devices certainly accomplish their desired purposes; however, the device of Knudtson incorporates rather extensive, complicated, and costly equipment while Sullivan incorporates a rather complicated handle. The device of Ramsey, which appears to be the simpler of the devices, provides for a mini or partial flush, however, the amount of water which is allowed to drain into the toilet bowl is not controlled with precision, it only being a function of how long it takes for sufficient air to escape from the cavity of the flapper valve non-buoyant so that it returns to its seated position terminating the outflow of water. Such operation of the invention is largely controlled by the size of the air vent hole and whether or not it becomes clogged.
In view of the foregoing, it would be useful to provide a simple device which allows for a full flush or a partial flush of a toilet at the option of the user at the time of use. In particular, it would be particularly useful if the amount of water which is to be incorporated in the partial flush be determined with relative precision and repeatable from flush to flush.